latexdiff with cite commands gives output with apparently mismatched braces

I have run into a problem with the markup that latexdiff adds around cite commands. The MWE below, which is supposed to have been generated by latexdiff, doesn’t compile because LaTeX doesn’t recognise the closing brace for DIFdel:

ERROR: Extra }, or forgotten endgroup.

The culprit is hspace{0pt}: commenting this out prevents this error.

I have solved my immediate problem by manually deleting the string hspace{0pt} from the difference file wherever it occurs, but obviously I’d rather not do this every time.

I have two questions: (1) why does LaTeX find a problem with the braces here in the first place, since they look matched to my human eyes (and to emacs!)? And (2) is there a way to prevent latexdiff from generating code that fails to compile in this way?

---

MWE for LaTeX (note that I’ve deleted most of the latexdiff preamble)

documentclass{article}

usepackage{hyperref}

% DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF
%DIF UNDERLINE PREAMBLE %DIF PREAMBLE
RequirePackage[normalem]{ulem} %DIF PREAMBLE
RequirePackage{color}definecolor{RED}{rgb}{1,0,0}definecolor{BLUE}{rgb}{0,0,1} %DIF PREAMBLE
providecommand{DIFdeltex}[1]{{protectcolor{red}sout{#1}}}                      %DIF PREAMBLE
%DIF SAFE PREAMBLE %DIF PREAMBLE
providecommand{DIFdelbegin}{} %DIF PREAMBLE
providecommand{DIFdelend}{} %DIF PREAMBLE
%DIF HYPERREF PREAMBLE %DIF PREAMBLE
providecommand{DIFdel}[1]{texorpdfstring{DIFdeltex{#1}}{}} %DIF PREAMBLE
%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF

begin{document}
DIFdelbegin DIFdel{Some textmbox{%DIFAUXCMD
cite{reference}}hspace{0pt}%DIFAUXCMD
, and some more text.}
DIFdelend

bibliography{my_bib}
end{document}

MWE for latexdiff

old.tex

documentclass{article}

usepackage{hyperref}

begin{document}
Some text cite{reference}, and some more text.

bibliography{my_bib}
end{document}

new.tex

documentclass{article}

usepackage{hyperref}

begin{document}
bibliography{my_bib}
end{document}

latexdiff old.tex new.tex > diff.tex

RequirePackage[normalem]{ulem} %DIF PREAMBLE
...
providecommand{DIFdeltex}[1]{{protectcolor{red}sout{#1}}} %DIF PREAMBLE

RequirePackage[2019/11/18]{latexrelease}